diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 6a35ba7..e6dfbea 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -151,6 +151,13 @@ jobs:
                  ndctl='${{ github.workspace }}'/ndctl \
                  ../run_qemu/run_qemu.sh -v --no-run ${{ matrix.run_opts }}
 
+      #  Test update_existing_rootfs(), default value for distro= and various other things
+      - name: incremental build
+        run: |
+          set -x
+          cd kernel
+          ../run_qemu/run_qemu.sh -v --no-run ${{ matrix.run_opts }}
+
       - name: ccache stats post build
         run: |
           # Pre-build stats printed at the start of the build step
diff --git a/run_qemu.sh b/run_qemu.sh
index 71be589..b80cc77 100755
--- a/run_qemu.sh
+++ b/run_qemu.sh
@@ -852,11 +852,11 @@ setup_depmod()
 	fi
 	if [ ! -f "$system_map" ]; then
 		echo "not found: $system_map. Try rebuilding with '-r img'"
-		return 1
+		# return 1
 	fi
 	: Warning: symlinks created by this depmod do not survive the move
 	: to the virtual machine
-	sudo depmod -b "$prefix" -F "$system_map" -C "$depmod_dir" "$kver"
+	sudo depmod -b "$prefix"                  -C "$depmod_dir" "$kver"
 }
 
 __update_existing_rootfs()